Laser Intensity Noise Suppression for Preparing Audio-Frequency Squeezed Vacuum State of Light

Bai, Lele; Xu, Wen; Yang, Yong; He, Jun; Wang, Junmin

doi:10.3390/app10041415

Cited by 6 publications

(4 citation statements)

References 36 publications

(33 reference statements)

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“…At the analysis frequency of 2 MHz, we have prepared 795-nm SVS with squeezing level of -5.6 dB [18]. However, the preparation of PSS at the audio-frequency is relatively difficult due to the challenging control of system noise and the serious coupling of ambient noise [19,24], we have demonstrated that the squeezing level of PSS can be improved experimentally by using the laser intensity noise suppression systems based on acousto-optic modulator [25]. In this work, SVS with squeezing level of -4.0±0.3 dB (the blue dash line) and anti-squeezing level of +7.0±0.3 dB (the pink dash line) can be obtained at the analysis frequency of 10 kHz by scanning the LO beam's phase, as shown by the red curve in figure 3 (a); PSS with relative noise power in S 2 is ∼ -3.7±0.3 dB (the noise level is about 0.43 times of SNL), as shown by the red line in figure 3 (b).…”

Section: Methodsmentioning

confidence: 99%

Quantum-enhanced rubidium atomic magnetometer based on Faraday rotation via 795-nm Stokes operator squeezed light

Bai,

Wen,

Yang

et al. 2021

Preprint

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With the help of Stokes operator S2 squeezed state (also called polarization squeezed state (PSS)) of 795-nm light, rubidium-87 ( 87 Rb) atomic magnetometer based on Faraday rotation has been implemented and characterized. The PSS of Stokes operator S2 of 795-nm light has been prepared by means of coherently combining the polarization coherent state (PCS) of a linearly p-polarized bright 795-nm light beam and a linearly s-polarized squeezed vacuum state (SVS) generated by a 397.5-nm ultraviolet laser pumped sub-threshold optical parametric oscillator (OPO) with a PPKTP bulk crystal inside the OPO cavity. PSS with a squeezing level of -3.7±0.3 dB has been achieved around the analysis frequency of 10 kHz. At different transitions of D1 line, various frequency detuning, and reasonable atomic vapor cell's temperature, Faraday rotation has been measured and compared. To decrease absorption (scattering) losses and the back-action from atomic spin noise to the probe beam's polarization noise for maintaining the quantum properties of PSS of Stokes operator S2 of 795-nm light, we had to run our magnetometer with 87 Rb vapor cell's temperature below 60 ℃, at which the PSS was almost destroyed. The sensitivities of magnetic field measurement were characterized via measuring signal-to-noise ratio of the alternating current (AC) calibrated magnetic field signal with a balanced polarimeter. Under the conditions of the atomic number density of ∼5.8×10 10 /cm 3 (T∼ 40 ℃) and the probe beam with a detuning of ∼ -400 MHz relative to the 5S 1/2 (Fg=2) -5P 1/2 (Fe=1) transition of 87 Rb D1 line, a typical sensitivity of ∼19.5 pT/Hz1/2 has been achieved employing PSS of Stokes operator S2 as the probe, compared with a sensitivity of ∼28.3 pT/Hz 1/2 using PCS as the probe. We preliminarily demonstrated that the quantum-enhanced sensitivity in a Faraday-rotation-based 87 Rb atomic magnetometer with the help of PSS of 795-nm light.

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Section: Methodsmentioning

confidence: 99%

Quantum-enhanced rubidium atomic magnetometer based on Faraday rotation via 795-nm Stokes operator squeezed light

Bai,

Wen,

Yang

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…At the analysis frequency of 2 MHz, we have prepared 795 nm SVS with squeezing level of −5.6 dB [18]. However, the preparation of PSS at the audio-frequency is relatively difficult due to the challenging control of system noise and the serious coupling of ambient noise [19,24], we have demonstrated that the squeezing level of PSS can be improved experimentally by using the laser intensity noise suppression systems based on acousto-optic modulator [25]. In this work, SVS with squeezing level of −4.0 ± 0.3 dB (the blue dash line) and anti-squeezing level of +7.0 ± 0.3 dB (the pink dash line) can be obtained at the analysis frequency of 10 kHz by scanning the LO beam's phase, as shown by the red curve in figure 3(a); PSS with relative noise power in Ŝ2 is ∼−3.7 ± 0.3 dB (the noise level is about 0.43 times of SNL), as shown by the red line in figure 3(b).…”

Section: Preparation Of 795 Nm Stokes Operator ŝ2 Polarization Squeez...mentioning

confidence: 99%

Quantum-enhanced rubidium atomic magnetometer based on Faraday rotation via 795 nm stokes operator squeezed light

Bai

Yang

et al. 2021

J. Opt.

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With the help of Stokes operator Ŝ2 squeezed state (also called polarization squeezed state (PSS)) of 795 nm light, rubidium-87 (87Rb) atomic magnetometer based on Faraday rotation (FR) has been implemented and characterized. The PSS of Stokes operator Ŝ2 of 795 nm light has been prepared by means of coherently combining the polarization coherent state (PCS) of a linearly p-polarized bright 795 nm light beam and a linearly s-polarized squeezed vacuum state (SVS) generated by a 397.5 nm ultraviolet laser pumped sub-threshold optical parametric oscillator (OPO) with a PPKTP bulk crystal inside the OPO cavity. PSS with a squeezing level of −3.7 ± 0.3 dB has been achieved around the analysis frequency of 10 kHz. At different transitions of D1 line, various frequency detuning, and reasonable atomic vapor cell’s temperature, FR has been measured and compared. To decrease absorption (scattering) losses and the back-action from atomic spin noise to the probe beam’s polarization noise for maintaining the quantum properties of PSS of Stokes operator Ŝ2 of 795 nm light, we had to run our magnetometer with 87Rb vapor cell’s temperature below 60 °C, at which the PSS was almost destroyed. The sensitivities of magnetic field measurement were characterized via measuring signal-to-noise ratio of the alternating current calibrated magnetic field signal with a balanced polarimeter. Under the conditions of the atomic number density of ∼5.8 × 1010 cm−3 (T ∼ 40 °C) and the probe beam with a detuning of ∼−400 MHz relative to the 5S1/2 (F g = 2) − 5P1/2 (F e = 1) transition of 87Rb D1 line, a typical sensitivity of ∼19.5 pT (Hz1/2)−1 has been achieved employing PSS of Stokes operator Ŝ2 as the probe, compared with a sensitivity of ∼28.3pT (Hz1/2)−1 using PCS as the probe. We preliminarily demonstrated that the quantum-enhanced sensitivity in a Faraday-rotation-based 87Rb atomic magnetometer with the help of PSS of 795 nm light.

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“…Similarly, the use of PSS of light can still improve the SNR of SNS without changing the FWHM. Typically, when the transverse magnetic field is 34.6 µ T, the corresponding Larmor precession frequency of 85 Rb is about 163 kHz, and the squeezing level of PSS we use is only -3.7 dB due to the coupling of various noises at this analytical frequency [26,27]. In order to effectively protect the quantum properties of PSS of light after passing through the atomic vapor cell and to ensure that paraffin film on the inner wall is not damaged [28], the temperature of cell we chose is 45 ℃.…”

Section: Quantum Enhanced Spin Noise Spectroscopymentioning

confidence: 99%

Enhancement of spin noise spectroscopy of rubidium atomic ensemble by using of the polarization squeezed light

Bai,

Zhang,

Yang

et al. 2021

Preprint

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We measured the spin noise spectroscopy (SNS) of rubidium atomic ensemble with two different atomic vapor cells (filled with the buffer gases or coated with paraffin film on the inner wall), and demonstrated the enhancement of signal-to-noise ratio (SNR) by using of the polarization squeezed state (PSS) of 795-nm light field with Stokes operator Λ S 2 squeezed. PSS is prepared by locking the relative phase between the squeezed vacuum state of light obtained by a sub-threshold optical parametric oscillator and the orthogonal polarized local oscillator beam by means of the quantum noise lock. Under the same conditions, PSS can be employed not only to improve SNR, but also to keep the full width at half maximum (FWHM) of SNS unchanged, compared with the case of using polarization coherent state (PCS), and the enhancement of SNR is positively correlated with the squeezing level of PSS. With the increase of probe laser's power and atomic number density, the SNR and FWHM of SNS will increase correspondingly. With the help of PSS of Stokes operator Λ S 2 , quantum enhancement of both SNR and FWHM of SNS signal has been demonstrated by controlling optical power of the Λ S 2 polarization squeezed light beam or atomic number density in our experiments.

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Laser Intensity Noise Suppression for Preparing Audio-Frequency Squeezed Vacuum State of Light

Cited by 6 publications

References 36 publications

Quantum-enhanced rubidium atomic magnetometer based on Faraday rotation via 795-nm Stokes operator squeezed light

Quantum-enhanced rubidium atomic magnetometer based on Faraday rotation via 795-nm Stokes operator squeezed light

Quantum-enhanced rubidium atomic magnetometer based on Faraday rotation via 795 nm stokes operator squeezed light

Enhancement of spin noise spectroscopy of rubidium atomic ensemble by using of the polarization squeezed light

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